Engine assembly and how an engine works.

Shamelessly nicked from frm:




So what, it's a cage, but interesting and well done, IMO.

On frm, the concensus is that the engine in the first clip is that of a
BMW. Confirmation anyone?

 

Brilliant! Haynes manuals should be like the first one - type in, for
example, "Cambelt change" and it shows you exactly what to do.

Si

 

Wonder if it provides info on changing gear box bearings without stripping
the motor? If not then maybe TOG should get in touch and offer his
"expertise" to cover this topic?

k

 

Errrmmmm, very dumb question, why are the cylinders spaced 180 apart and
not 90? I kind of had it in my head that thats how they were.

 

Bloody good, is that.

No idea....

 

Degrees?

Balance.
Some are at 90.

 

For balance and equal firing intervals. They're all like that.
You're thinking of half a V8.

 

Dunno, but I've got the original screensaver of that at work somewhere. I'll
see if I can dig it out, it may give a clue.

 

That's pretty much what I thought, but for the life of me I can't think
why it improves balance. Cheers anyway, I'll google it in my free time.

<pauses> and inline 6?

 

View a single-cylinder engine from the front (or rear). Crank goes around,
piston and rod goes up and down. The crank has a counterweight that
balances the mass of the piston and rod (and some of the mass of the crank
itself) at TDC and BDC. But at all other angles, the counterweight is
swinging to the left or to the right of centre, with insufficient opposing
mass to balance it. Add another cylinder, 180 degrees from the first. Now
the counterweights balance each other out. But the cylinders (obviously)
don't lie in the same plane, so there's a 'couple', which attempts to make
each end of the crankshaft (and hence the engine) trace out a cone. So now
add another two cyliners, just like the first pair, arranged 0-180-180-0.
Now the couples balance each other out.

Perfect balance? Not quite. Although the four-cylinder 0-180-180-0 engine
has good primary balance, there is a second-harmonic vibration, which is
caused by the fact that the pistons' vertical motion is not harmonic (i.e.,
the vertical displacement of the piston, when plotted against crank-angle,
is not a sine wave). The engine does not have perfect secondary balance.
One way to reduce this problem is with a harmonic balancer-shaft (or
shafts), geared to spin at twice the rate of the crank.

Has perfect primary and secondary balance (with a 0-240-120-120-240-0
crank).